A woman was robbed of her mobile phone as she walked near the Racecourse in Northampton.
The 25-year-old victim was walking along East Park Parade between 2 and 3am on Sunday when she was beckoned into the Racecourse by a man who then threatened to hurt her unless she handed over her phone.
The offender is described as white, aged between 18 and 25, about 5ft 11in tall with an average build and short, fair or ginger hair. He had a pale complexion with some facial hair and was wearing a dark-grey tracksuit.
Police are keen to trace a couple who assisted the victim following the incident and ask that they contact police.
Witnesses or anyone with information is asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.